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INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY in conjunction with
THE NATIONAL RESEARCH COUNCIL OF CANADA and
THE CHEMICAL INSTITUTE OF CANADA
COORDINATION CHEMISTRY—XIV
Plenary lectures presented at the XlVth INTERNATIONAL CONFERENCE ON COORDINATION CHEMISTRY held at Toronto, Canada 22-28 June 1972 Symposium Editor A. B. P. LEVER
York University, Ontario
LONDON
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The contents of this book appear in
Pure and Applied Chemistry, Vol. 33, No. 4 (1973) Suggested U.D.C, number: 541-49 (063)
International Union of Pure and Applied Chemistry 1973
ISBN: 0 408 70470 5
Printed in Great Britain by Page Bros (Norwich) Ltd., Norwich
ORGANIZING COMMITTEE Chairman: C. J. L. LOCK
Members: T. B. C. D. R.
BlRCHALL BOSNICH D. COOK R. EATON HARRIS
H. E. HOWARD-LOCK A. B. P. LEVER J. A. PINDER J. POWELL J. C. THOMPSON A. WALKER
SYNTHESIS AND PROPERTIES OF TRANSITION METAL TO CARBON BONDS F. CALDERAZZO
Istituto di Chimica Generale ed Inorganica,
Università di Pisa, 56100 Pisa
ABSTRACT The known properties of alkyl and aryl derivatives of transition elements are reviewed, with particular attention to binary compounds of this type. Factors contributing to thermal stability of metal-carbon σ-bonds are discussed and new contributions are presented dealing with: (/) chemistry of titanium(iv) and titanium(n); (ii) metal-carbon bonds in A^A^-ethylenebis(salicylideneiminato) complexes of iron and cobalt; (Hi) reactivity of rhenium(i) bromo-carbonyl complexes; (zv) use of metal carbonyls as a source of zerovalent metals in the preparations of binary complexes of 9,10-phenanthrenequinone and (v) syn thesis of cyclopentadienyl-alkyl and cyclopentadienyl-aryl derivatives of uranium(iv).
INTRODUCTION In the past decades chemists have lived in the belief that alkyl and aryl derivatives of transition metals had to be unstable. This belief came from the observation that while several organometallic compounds of non-transi tion elements were known and were thermally stable under ordinary condi tions, pure binary compounds of transition elements had been until quite recently a rarity. Some of them have been recently synthesized, however (see Table 1). Some examples of non-binary alkyl and aryl derivatives of transition metals are given in Tables 2 and 3. Although the Tables contain only a limited number of selected examples, some interesting observations can be made. Table 1. Some binary alkyl derivatives of d-transition elements Compound Ti(CH 2 C 6 H 5 ) 4 Zr(CH 2 C 6 H 5 ) 4 Cr(CH 2 SiMe 3 ) 4 WMe 6
Colour red-brown yellow dark-purple red
m.p.(°C)
Reference
70-71 133-134 38 c.30 (dec. 50)
1 1 2a, 2b 3
(i) Stable organometallic compounds of transition metals exist even with 453
PAC—33—4—B
F. CALDERAZZO Table 2. Some non-binary alkyl and aryl compounds of d-transition elements in their highest usual oxidation states Compound Ti(C 5 H 5 ) 2 (CH 2 C 6 H 5 ) 2 Zr(C 5 H 5 ) 2 (CH 2 C 6 H 5 ) 2 Zr(C 5 H 5 ) 2 Me 2 VO(CH 2 SiMe 3 ) 3 FeSaEn-CH 2 C 6 H 5 t CoSaEn-Me Ni(lipy)Me2 Pt(PR 3 ) 2 Me 4 Pt(C 5 H 5 )Me 3 Au 2 Me 6 (NH 2 CH 2 CH 2 NH 2 ) Au(PMe 3 )Me 3 Au(PPh 3 )(C 6 F 5 ) 3
C